CN104009482B - Method for dynamically setting gateway reactive power control range under single-line and single-variable wiring mode - Google Patents

Abstract

The invention provides a method for dynamically setting a gateway reactive power control range under a single-line and single-variable wiring mode. The problem that the dynamic variation of power grid operation characteristics can not be adapted due to the fact that the gateway reactive power control range is fixed in automatic voltage control of a current power grid is solved. The method comprises the specific steps that first, the parameter of a regional power grid circuit, the parameter of a main transformer and the voltage data of an electricity sending end are collected; second, the minimum value of system active power loss of the main transformer under different load rates, the gateway reactive power optimal section, and the corresponding gateway power factor variation range are calculated; at last, the gateway power factor constraints of the transformer in the low load process and in the heavy load process are considered, and the gateway reactive power control ranges under different working conditions are obtained. According to the method for dynamically setting the gateway reactive power control range under the single-line and single-variable wiring mode, the gateway reactive power optimal control range can be dynamically adapted to the variation of power grid load levels, and reactive power balance, energy saving and consumption reduction of the system can be promoted.

Description

Critical point idle span of control dynamic tuning method under a kind of monotropic mode of connection of single line

Technical field

The present invention relates to power system critical point powerless control method, particularly to critical point under a kind of monotropic mode of connection of single line Idle span of control dynamic tuning method.

Background technology

With the continuous expansion of electrical network scale, the safety of operation of power networks, reliability and economy problems have become all the more Prominent, and tradition carries out the method for centralized optimization not only feasibility is low after whole complex large power grid is modeled but also control effect Poor.Comparatively speaking, the vqc control strategy based on the local electric information of transformer station, the idle in-situ balancing of pursuit, due to modeling Less demanding, information interaction amount is few, control algolithm is simple, has obtained wide at present in the reactive power/voltage control of avc transformer substation side General application.

However, there is an obvious problem in the method: for the interval setting of critical point reactive power be often basis with Past operating experience and lack the guidance of theoretical foundation, do not account for that electric network element parameter is different and operation characteristic change is to no yet The diversity of work(demand for control, this can lead to the safety of system operation (to be related to abundance, the voltage amplitude of dynamic reactive deposit Qualification rate of value etc.), reliability (avoiding the frequent regulation of equipment) and economy (reduce and run power attenuation) tend not to To coordination optimization.

The present invention proposes the idle span of control in critical point dynamic tuning method under a kind of monotropic mode of connection of single line, for this The different operating condition of system provides the idle span of control in adaptable critical point, thus avoiding because of the change of network load level The idle upper lower limit value in critical point causing sets irrational problem.This setting method is applicable not only to that single line is monotropic also can be pushed away simultaneously Wide to other more complicated modes of connection such as: the double change of single line, two-wire three become and chain wiring and t type wiring etc., have Stronger engineering application value.

Content of the invention

It is an object of the invention to the idle span of control in critical point solving to lead to because of the change of network load level does not conform to The problem of reason, proposes a kind of single-phase electricity and becomes critical point idle span of control dynamic tuning method under the mode of connection, concrete technical scheme As follows.

A kind of single-phase electricity becomes critical point idle span of control dynamic tuning method under the mode of connection, comprises the following steps:

(1) the resistance r of collection circuit, reactance x, node susceptance b, the capacity s of transformator_n, open circuit loss p₀, load loss p_k, short-circuit voltage percentage value u_k%, no-load current percentage value i₀% and its power transmission terminal voltage u_a；

(2) select in transformer load rate β=10%, 40% and the lighter state 1 of 70% 3 kind of level representation load, load Etc. state 2 and the heavier state of load 3, circuit and transformer active under three kinds of load conditions are asked for respectively using graphing method it is lost Minima p of sum_lmin1、p_lmin2、p_lmin3；Calculate optimum network loss offset delta p_l；

(3) calculate the idle q in critical point under three kinds of load conditions respectively_hOptimization interval And corresponding critical point power factor change scope

(4) judgeWhether delayed, if meeting, β < when 40%, the idle span of control in critical point is:If being unsatisfactory for, β < when 40%, the idle span of control in critical point is:

(5) judgeWhether it is not less than 0.95, if meeting, during β >=40%, the idle span of control in critical point is:If being unsatisfactory for, the span of control that critical point during β >=40% is idle is:DescribedForWhen critical point reactive power.

Further, under different loads rate in described step (2), circuit and transformer active are lost the minima of sum p_lminAnd optimum network loss offset delta p_lObtained according to following methods:

When power transmission terminal voltage u_aWhen known, active loss sum p of circuit and transformator_lIt is represented by:

p_l=△p_t+△p_l(1),

$\mathrm{\&delta;}{p}_t=p_o+p_k\frac{p_d^2+{(q_h-\mathrm{\&delta;}{q}_t)}^2}{s_n^2}---\left(2\right),$

$\mathrm{\&delta;}{q}_t==\frac{i_0\%}{100}\&centerdot;s_n+\frac{u_k\%}{100}\&centerdot;\frac{p_d^2+{(q_h-\mathrm{\&delta;}{q}_t)}^2}{s_n}---\left(3\right),$

$\mathrm{\&delta;}{p}_l=\frac{{(p_d+\mathrm{\&delta;}{p}_t)}^2+{(q_h-{{\mathrm{bu}}_b}^2/2)}^2}{{u_b}^2}r---\left(4\right),$

$u_b=u_a-\frac{(p_d+\mathrm{\&delta;}{p}_t)r+(q_h-{{\mathrm{bu}}_b}^2/2)x}{u_a}---\left(5\right),$

$\mathrm{\&beta;}=\frac{s_d}{s_n}\&times;100\%---\left(6\right),$

Formula (1) to (8) comprising variable: transformer active loss δ p_t；Circuit active loss δ p_l；Receiving end voltage u_b；Become Depressor reactive loss δ q_t；Load apparent energy s_d；Load active power p_d；Reactive load power q_d；Load power factor

Understand, when in system, network element parameter and burden with power give, to close by change according to formula (1) to (4) Mouthful idle q_hAmount try to achieve p_lWith the idle q in critical point_hThe u-shaped pattern changing and changing, the minimum point of this curve is just p_lMinima p_lmin, this determines p_lminMethod be graphing method, described optimum network loss offset delta p_lIdle for critical point under different loads rate Optimize the active loss p corresponding to each point in interval_lWith respect to minima p_lminMaximal increment, can be obtained by formula (9):

δp_l=α %p_lmin3(9),

Formula (9) comprising variable: the minima of circuit and transformer active loss sum during transformer load rate β=70% p_lmin3；The artificial constant α % setting of power conservation requirement when being run according to system reload.

Further, the idle q in critical point under different loads rate in described step (3)_hOptimization interval can be by with lower section Method obtains: when in system, network element parameter and burden with power give, active loss sum p of circuit and transformator_lCan see It is the idle q in critical point_hFunction of a single variable, and by change the idle q in critical point_hAmount can try to achieve p_lWith the idle q in critical point_hChange and change U-shaped pattern, can determine p from this curve_lMinima p_lmin, according to given optimum network loss offset delta p_l, mark p_lminWith δ p_lThe contour of sum and u-shaped pattern intersect at 2 points, and in the abscissa of two intersection points, larger and smaller corresponds to respectively The interval upper limit value and lower limit value of critical point idle work optimization.

Further, described step (4), the implementation process of (5) are:

(1) judgeWhether delayed:

If meeting, during transformer station's underloading, the idle span of control in critical point is:

If being unsatisfactory for, during transformer station's underloading, the idle span of control in critical point is:

(2) judgeWhether not less than 0.95:

If meeting, during transformer station's non-underloading, the idle span of control in critical point is:

If being unsatisfactory for, during transformer station's non-underloading, the idle span of control in critical point is: Described 'sForWhen critical point reactive power；

Wherein, using transformer load rate β=40% as the separation of transformer station's underloading and non-underloading.

Compared with prior art, present invention has the advantage that

(1) consider the impact to the idle control in critical point for the operation of power networks characteristic variations, can be for different operating conditions Make the idle span of control in adaptable critical point.

(2) the idle span of control dynamic tuning method in proposed critical point, not only allows for critical point work(when light transformer, heavy duty Controlling of rate factor requires it is also possible to avoid the frequent of low-pressure side reactive power compensator while meeting system operation economy Action.

Brief description

Fig. 1 is the idle span of control in critical point dynamic tuning method flow diagram in the monotropic mode of connection of single line.

Fig. 2 is idle work optimization interval diagram in critical point under certain load factor.

Fig. 3 is certain monotropic mode of connection schematic diagram of 110kv electrical network single line.

Specific embodiment

Below in conjunction with accompanying drawing and example to the present invention be embodied as be described further, but the enforcement of the present invention and protection Not limited to this.

As Fig. 1, critical point idle span of control dynamic tuning method in a kind of monotropic mode of connection of single line, walk including following Rapid:

(1) the resistance r of collection circuit, reactance x, node susceptance b, the capacity s of transformator_n, open circuit loss p₀, load loss p_k, short-circuit voltage percentage value u_k%, no-load current percentage value i₀% and its power transmission terminal voltage u_a；

(2) select in transformer load rate β=10%, 40% and the lighter state 1 of 70% 3 kind of level representation load, load Etc. state 2 and the heavier state of load 3, circuit and transformer active under three kinds of load conditions are asked for respectively using graphing method it is lost Minima p of sum_lmin1、p_lmin2、p_lmin3；Calculate optimum network loss offset delta p_l；

As shown in Fig. 2 in figure dotted line and chain-dotted line respectively indication transformer loss and line loss, solid line represent total losses (transformator and line loss sum), because two groups of numerical value difference are larger, is represented using major-minor axis of ordinates to represent convenient. As seen from the figure, when system parameters give, active loss sum p of circuit and transformator_lThe idle q in critical point can be regarded as_hUnitary Function, and by changing the idle q in critical point_hAmount can try to achieve total losses p_lWith the idle q in critical point_hThe u-shaped pattern changing and changing, its Middle p_lminIt is this total losses value corresponding to curve minimum point, optimum network loss offset delta p_lCan be obtained by following formula:

δp_l=α %p_lmin3

In formula, p_lmin3Minima for circuit during transformer load rate β=70% and transformer active loss sum；α % It is the artificial constant setting of power conservation requirement when being run according to system reload；

(3) calculate respectively and ask for the idle q in critical point when transformer load rate β=10%, 40% and 70%_hOptimization intervalAnd corresponding critical point power factor change scope

As shown in Fig. 2 according to optimum network loss offset delta p set in advance_l, mark p_lminWith δ p_lThe contour of sum Intersect at 2 points with u-shaped pattern, in the abscissa of two intersection points larger and smaller correspond to respectively critical point idle work optimization interval upper, Lower limit.

(4) judgeWhether delayed, if meeting, β < when 40%, the idle span of control in critical point is:If being unsatisfactory for, β < when 40%, the idle span of control in critical point is:

(5) judgeWhether it is not less than 0.95, if meeting, during β >=40%, the idle span of control in critical point is:If being unsatisfactory for, the span of control that critical point during β >=40% is idle is:DescribedForWhen critical point reactive power.

Further, described step (4), the implementation process of (5) are:

(1) judgeWhether delayed.

If meeting, during transformer station's underloading, the idle span of control in critical point is:

If being unsatisfactory for, during transformer station's underloading, the idle span of control in critical point is:

(2) judgeWhether it is not less than 0.95.

If meeting, during transformer station's non-underloading, the idle span of control in critical point is:

If being unsatisfactory for, during transformer station's non-underloading, the idle span of control in critical point is: Institute StateForWhen critical point reactive power.

Wherein, using transformer load rate β=40% as the separation of transformer station's underloading and non-underloading.

The following is an example of calculation of the inventive method, taking the monotropic mode of connection of single line in certain 110kv electrical network as a example, figure 3 topological structure showing this mode of connection.

(1) the resistance r of collection circuit, reactance x, node susceptance b, the capacity s of transformator_n, open circuit loss p₀, load loss p_k, short-circuit voltage percentage value u_k%, no-load current percentage value i₀% and its power transmission terminal voltage u_a, have:

R=0.8 ω, x=3.98 ω, b=2.91 × 10^-5S, s_n=50mva, p₀=25kw

p_k=178.4kw, u_k%=16, i₀%=0.01, u_a=115kv

(2) select in transformer load rate β=10%, 40% and the lighter state 1 of 70% 3 kind of level representation load, load Etc. state 2 and the heavier state of load 3, circuit and transformer active under three kinds of load conditions are asked for respectively using graphing method it is lost Minima p of sum_lmin1、p_lmin2、p_lmin3；Calculate optimum network loss offset delta p_l；

β=10%:p_lmin1=28kw；β=40%:p_lmin2=73kw；β=70%:p_lmin3=173kw makes constant α %= 6% optimum network loss side-play amount is:

δp_l=α %p_lmin3=173 × 6%kw ≈ 10kw

(3) calculate respectively and ask for the idle q in critical point when transformer load rate β=10%, 40% and 70%_hOptimization intervalAnd corresponding critical point power factor change scope

Optimum network loss offset delta p when given system_lDuring=10kw, the idle optimization in critical point under different loads rate can be obtained Interval and corresponding critical point power factor change scope is as shown in table 1.

The optimization that under table 1 different loads rate, critical point is idle is interval

Transformer load rate β	10%	40%	70%
				Optimize interval/mvar	(- 8.5,9.0)	(- 7.5,9.5)	(- 6.5,10.5)
Power factor is interval	(0.47,0.49)	(0.89,0.93)	(0.95,0.98)

Note: in table, runic numerical value represents that power factor is advanced

(4) judgeWhether delayed, if meeting, β < when 40%, the idle span of control in critical point is:If being unsatisfactory for, β < when 40%, the idle span of control in critical point is:Due toIn advance, then β < when 40%, the idle span of control in critical point is: (0,9) ∩ (- 7.5,9.5)=(0,9).

(5) judgeWhether it is not less than 0.95, if meeting, the idle control model in critical point when can directly obtain β >=40% Enclose for:If being unsatisfactory for, the span of control that critical point during β >=40% is idle is:WhereinForWhen critical point reactive power.Due toCause The critical point idle work optimization interval of this β=70% is still (- 6.5,10.5), then during β >=40%, the idle span of control in critical point is: (- 6.5,10.5) ∩ (- 7.5,9.5)=(- 6.5,9.5).

Using transformer load rate β=40% as the separation of transformer station's underloading and non-underloading, then in the case of different loads Critical point critical point span of control as shown in table 2.

The idle span of control in critical point under the different operating condition of table 2

Loading condition	Critical point is idle span of control/mvar	(pl-plmin)/kw
			β < 40% (underloading)	(0,9)	≤10
β >=40% (non-underloading)	(- 6.5,9.5)	≤10

As shown in Table 2, critical point idle span of control dynamic tuning under a kind of monotropic mode of connection of single line proposed by the present invention Method can make the idle span of control in adaptable critical point for different operating condition in the monotropic mode of connection of single line, and Ensure to meet the economy of system operation in this span of control, be also avoided that frequently moving of low-pressure side reactive power compensator Reactive power releasing problem when work and transformer station's underloading.This setting method is applicable not only to that single line is monotropic also to extend to it simultaneously His more complicated mode of connection is such as: single line is double to be become, two-wire three becomes and chain wiring and t type wiring etc., has stronger Engineering application value.

Above-described embodiment is the present invention preferably embodiment, but embodiments of the present invention are not subject to above-described embodiment Restriction, the modification made under other any spirit without departing from the present invention and principle, modification, replacement, combination, simplification, all Should be equivalent substitute mode, all should be included within protection scope of the present invention.

Claims (2)

1. under a kind of monotropic mode of connection of single line critical point idle span of control dynamic tuning method it is characterised in that including following walking Rapid:

(1) the resistance r of collection circuit, reactance x, node susceptance b, the capacity s of transformator_n, open circuit loss p₀, load loss p_k, short Road voltage percentage value u_k%, no-load current percentage value i₀% and its power transmission terminal voltage u_a；

(2) transformer load rate β=10%, 40% and the lighter state 1 of 70% 3 kind of level representation load, the medium shape of load are selected State 2 and the heavier state of load 3, ask for circuit and transformer active under three kinds of load conditions respectively using graphing method and sum are lost Minima p_lmin1、p_lmin2、p_lmin3；Calculate optimum network loss offset delta p_l；Circuit and transformer active loss under different loads rate Minima p of sum_lminAnd optimum network loss offset delta p_l, obtained according to following methods:

When power transmission terminal voltage u_aWhen known, active loss sum p of circuit and transformator_lIt is represented by:

p_l=δ p_t+δp_l... ... ... ... ... ... ... ... (1),

Formula (1) to (8) comprising variable: transformer active loss δ p_t；Circuit active loss δ p_l；Receiving end voltage u_b；Transformator Reactive loss δ q_t；Load apparent energy s_d；Load active power p_d；Reactive load power q_d；Load power factor

Understand when in system, network element parameter and burden with power give according to formula (1) to (4), can be by changing critical point no Work(q_hAmount try to achieve p_lWith the idle q in critical point_hThe u-shaped pattern changing and changing, the minimum point of this curve is just p_lMinima p_lmin, This determines p_lminMethod be graphing method；

Described optimum network loss offset delta p_lActive damage corresponding to each point in idle work optimization interval in critical point under different loads rate Consumption p_lWith respect to minima p_lminMaximal increment, can be obtained by formula (9):

δp_l=α %p_lmin3... ... ... ... ... ... .... (9),

Formula (9) comprising variable: minima p of circuit and transformer active loss sum during transformer load rate β=70%_lmin3； According to the artificial constant α % setting of power conservation requirement during single line monotropic system heavy service；

(3) calculate the idle q in critical point under described three kinds of load conditions respectively_hOptimization interval And corresponding critical point power factor change scope

(4) judgeWhether delayed, if meeting, β < when 40%, the idle span of control in critical point is:If being unsatisfactory for, β < when 40%, the idle span of control in critical point is:

(5) judgeλ _h3Whether it is not less than 0.95, if meeting, during β >=40%, the idle span of control in critical point is:If being unsatisfactory for, the span of control that critical point during β >=40% is idle is:DescribedForλ _h3Critical point reactive power when=0.95.

2. critical point idle span of control dynamic tuning method under the monotropic mode of connection of single line according to claim 1, it is special Levy and be: the idle q in critical point under described different loads rate_hOptimization interval be prepared by the following: when network element in system When part parameter and burden with power give, by active loss sum p of circuit and transformator_lRegard the idle q in critical point as_hFunction of a single variable, And by changing the idle q in critical point_hAmount try to achieve p_lWith the idle q in critical point_hThe u-shaped pattern changing and changing, can determine that from this curve p_lMinima p_lmin, according to given optimum network loss offset delta p_l, mark p_lminWith δ p_lThe contour of sum and u-shaped pattern Intersect at 2 points, larger and smaller's interval upper limit value and lower limit value of corresponding critical point idle work optimization respectively in the abscissa of two intersection points.